This invention relates to apparatus and methods for taking dental impressions and, more specifically, for taking registered impressions of upper and lower teeth in full occlusion and converting these impressions into castings which are used for analysis by the dentist, displays for patient consultations, laboratory work, and, when properly mounted and registered, for correct bite registration. Present methods for preparing these castings require taking upper and lower impressions with separate sequentially applied trays filled with an impression material. Upon hardening, a separate plaster casting is poured for each tray. It is often desirable to register the castings so that they fit together in the same manner as if in the patient's mouth. This has previously been accomplished by placing a relatively thin sheet of wax between the teeth and having the patient bite into the wax to form simultaneous indentations in the wax of both the upper and lower cusp tips of the teeth as they fit together. This wax bite impression is then employed to register the upper and lower dental casts in their proper occlusion. With the wax bite in place between the teeth castings, the castings are trimmed on their posterior faces as well as other surfaces to form artistic occlusally registered models. An articulator may also be attached to the castings to allow them to hinge. This procedure entails a large amount of time, labor, cost, sometimes patient discomfort, and has many opportunities for inaccuracy of registration, all of which are greatly reduced by the system disclosed herein.